No. 1.] MORPHOLOGY 7OF CLADOSELACHE, 99 
stout parallel rays of cartilage which form the inferior lobe of 
the tail, but disappear in the hinder web midway from tip to 
tip. In Cladoselache these are about twelve in number, the 
middle pair being the longest, the remainder extending in 
graded sizes to and from the lobe tip. They are unjointed ; 
of their connection with the haemal arches no satisfactory 
determination may be made; it appears, however, that they 
were attached at no great distance from the notochordal 
sheath. Rudimentary structures pass caudad; four are seen 
to be separable as basal supports ; a terminal cartilage bar is 
closely apposed to the chord. 
Unfortunately the upper lobe of the tail cannot be compared 
with that of Acanthodes, since the epural structure in the 
latter.is obscured by the crusting remains of shagreen. In 
the present case nearly two-thirds of the lobe breadth is 
formed of a compact row of epural cartilages. These supports 
are readily to be reduced to proximal and distal elements, 
and indicate as well traces of a second proximal division, 
making the entire epural structure comparable in its elements 
to radalia, basalia, with perhaps included axonosts. Of the 
distal elements about fourteen may be defined, and appear 
to be curiously homodynamous with foremost radials of the 
pectoral ; thus the foremost are the shortest and stoutest and 
are directed forward, blunt ended, while those succeeding 
come to be gradually elongated and directed more and more 
caudad. The row of basal elements is less readily separable, 
seven plates perhaps may here be included, although doubt- 
fully ; and of the proximal row nothing is positively definable. 
The membrane-like posterior margin of the caudal extends 
between the tail lobes in a straight line from tip to tip; in 
the upper lobe it reaches proximad to the sub-notochordal 
cartilage ; in the lower it gives the rays a distal derm 
margin of about ¥% inch. It is particularly interesting to 
note that here again appear the beginnings of dermal rays 
(trichinosts) extending in the same direction as indicated in 
recent forms. They are so fine in character that they are 
scarcely to be seen by the unaided eye (240 to an inch). 
They exhibit no branching or jointed structure. The actual 
